Follistatin-like protein 1 is elevated in systemic autoimmune diseases and correlated with disease activity in patients with rheumatoid arthritis

Table 1 Characteristics and serum FSTL1 levels of the subjects investigated^a

Characteristics	RA	ReA	PsA	AS	CD	UC	SLE	pSS	sSS	SSc	PM/DM	HC
Total number of subjects	207	22	34	33	20	22	40	16	28	22	43	69
Age^b, years	54	23.5	46.5	44	33	35	37	50	53	53.5	41	38
25th percentile	43.5	13.8	33	29.5	25.5	29.3	31.3	48	39.3	43.5	26	27
75th percentile	63	33.5	54	51	43	45.8	52.3	63	63	58	58	41
Number of female/male subjects	159/48	8/14	15/19	9/24	6/14	9/13	34/6	14/2	24/4	17/5	31/12	37/32
Disease duration^b, years	3	20 days	5	2	3	4	4	2	3	2	1	-
25th percentile	0.5	13 days	3	1	1	2	1	1	1	1	0.3	-
75th percentile	10	75 days	7	4	6	7	6	4	8	5	2	-
Serum FSTL1 levels, μg/l
Geometric mean	74.28	3.74	7.57	6.19	6.39	13.61	14.60	29.94	73.88	16.48	13.79	6.49
Lower 95% CI	60.89	2.73	4.99	5.03	5.35	9.71	10.49	15.76	45.79	7.81	9.97	5.89
Upper 95% CI	90.60	5.12	11.48	7.62	7.63	19.06	20.30	56.88	119.20	34.76	19.06	7.15
RSD (%)	129.17	104.58	134.90	63.33	39.06	112.35	115.27	148.22	117.81	133.00	186.28	36.71
Median	71.27	3.71	4.52	5.21	6.05	10.78	12.92	34.81	82.48	25.01	10.74	6.60
25th percentile	25.51	2.49	3.47	3.67	4.92	7.48	6.84	10.51	23.48	3.38	6.76	5.28
75th percentile	236.70	5.46	29.59	9.37	8.55	28.24	34.12	47.37	169.70	62.68	29.60	8.19
Above normal, %^c	87.43	9.09	26.47	18.18	5	36.36	52.5	68.75	96.43	54.55	48.84	4.3
P versus HC	<0.001	<0.001	0.100	0.375	0.627	<0.001	<0.001	<0.001	<0.001	<0.001	0.018	-
P versus RA	-	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	0.013	0.937	<0.001	<0.001	<0.001

^aFSTL1, follistatin-like protein 1; 95% CI, 95% confidence interval; -, not determined; RSD, relative standard deviation; HC, healthy individuals; RA, rheumatoid arthritis; ReA, reactive arthritis; PsA, psoriatic arthritis; AS, ankylosing spondylitis; CD, Crohn's disease; UC, ulcerative colitis; SLE, systemic lupus erythematosus; pSS, primary Sjögren's syndrome; sSS, secondary Sjögren's syndrome; SSc, systemic sclerosis; PM/DM, polymyositis/dermatomyositis; ^bmedian; ^cnormal range denoted as mean + 2 SD was 12 μg/l.